iStock/Thinkstock(NEW YORK) -- Screaming, crying, tantrums -- parents are all too familiar with the meltdown that ensues as a result of toddlers skipping needed naps.

Now, a small new study suggests that there may be another downside. For preschoolers, skipping nap time could have a negative impact on their ability to learn.

University of Massachusetts Amherst cognitive neuroscientist Rebecca Spencer led a study of 40 preschoolers to tease out the relationship between napping and the ability of these kids to learn something and remember it later.

All of the children were instructed on a task in the beginning of the experiment. Half were allowed to nap, while the other half were not. What Spencer and her colleagues found when they tested the kids on their abilities on the task was that memory performance was better for children who took a midday nap than those who did not, even when tested 24 hours later.

Moreover, when the researchers separated the children who habitually napped from those who didn’t, the benefit was greatest for children who napped at least five days per week.

This study, published Monday in the Proceedings of the National Academy of Sciences, comes at a time when many preschools across the country are reducing nap times -- or, in some cases, cutting them out entirely. Past research has suggested that adequate sleep is important in learning for young adults, but never before has research directly linked napping to preschool children’s memory.

“Naps are serving the academic goals that preschools have,” said Spencer, who added that the new research shows the benefits of providing and promoting naps for preschoolers. “This will hopefully be the science to protect naps in the classroom” for preschoolers.

Pediatric sleep experts not involved in the study said the findings make sense.

“There is similar data about importance of slow-wave sleep overnight and its role in memory consolidation,” said Dr. Suresh Kotagal, a pediatric neurologist and sleep disorder specialist at the Mayo Clinic. He added that the new research extends previous studies that show the value of proper sleep in adolescents and adults.

But even if you lead a kid to nap time, can you make him nap?

Ellen Frede is the senior vice president of early learning, research and training at Acelero Learning, a company that provides research and support for government initiatives pertaining to educational programs. She is also a former preschool teacher, and she noted that forced midday naps can be “torture for some children,” particularly those children who have already outgrown them.

As a result, she urges those in schools to “be careful how [they] apply this to the individual.” She also cautions parents from “getting stressed out about ‘making’ their children nap and being unable to do it.”

Lead study author Spencer, for one, acknowledged that in the classroom setting it may be difficult to figure out which preschool children actually need a nap, and which may have outgrown it. She said further research is needed so that children who might not need a nap can be distinguished from those who simply don’t want to -- but might benefit from some midday sleep.